Our laboratory is elucidating the nature of the immune response to murine tumors and establishing principles which may enhance our ability to immunize patients against known tumor antigens. We have used therapeutic cytotoxic T-lymphocyte lines to identify tyrosinase-related protein 2 (TRP-2) as a tumor T-cell-antigen from the B16 melanoma by immuno-screening a cDNA library from this tumor. In a parallel system, we also found that the transmembrane component of a retroviral envelope protein, encoded by a C57BL/6 germline gene was a tumor-associated T- cell antigen for a large number of murine tumors of different histologies (colon adenocarcinoma, fibrosarcoma and melanoma). For each of these tumor antigen models, we have also defined the minimal determinant peptide recognized and used it to generate CTL which were therapeutic for the parental tumor in vivo in adoptive cellular transfer experiments. Subsequent studies defined the nature of the CTL responses to these minimal determinants in naive and tumor-immune animals and described CTL avidity for the peptide-MHC complex as the prime discriminant of anti-tumor immunity in these systems. Experiments showed that in vitro stimulating peptide concentrations modulated the avidity of the CTL generated and that range of CTL avidities in tumor- immunized mice was higher than in naive and other non-immune mice. Continuing work on murine pre-clinical tumor antigen models has also identified murine Cathepsin L (also described as Major Excreted Protein [MEP] and mouse cysteine proteinase), as a tumor-antigen recognized by a T-cell clone reactive with the MC38 murine colon carcinoma. The latest studies have also identified a novel protein (currently termed colon cancer antigen, CCA) as an antigen of the MC-38 tumor recognized by a T-cell. We have determined the Db-restricted minimal determinant in CCA which is recognized and are studying its immunogenicity, expression profile and looking for a human homolog.In other studies, we developed methodologies for identifying tumor-specific CTL from patients with renal cell cancer and successfully used these techniques to identify an RCC-associated T-cell antigen. Unmutated FGF-5 was recognized in an HLA-A3 restricted fashion by RCC TIL from a patient showing spontaneous tumor regression). FGF-5 was expressed in 60% of RCC lines and in some other breast and prostate cancer lines which also were immunolgically recognized when transduced with HLA-A3. We are trying to identify specific epitopes for FGF-5 for vaccine development. In addition, FGF-5 has transforming, angiogenic and autocrine/paracrine tumor promoting activity in other systems, so we are exploring strategies for neutralizing its bioactivity as a therapeutic strategy (see next project).In addition to the above work, clinical studies investigating the optimal IL-2 regimen for inducing the regression of advanced renal cell cancer are also ongoing. A prospective randomized 3-arm trial comparing subcutaneous IL-2 versus high and low- dose intravenous IL-2 in the treatment of metastatic renal cell cancer is nearing its full accrual of 400 patients. This represents the only study to address the most effective way to administer IL-2, which is likely to be an important component of any combination immunotherapy strategy for advanced RCC. - immune response, immunotherapy,